Scientific considerations on a technique of ecological purification that made possible the cultivation of reef-building corals in Monaco

For the last 50 years powerful mechanical filtration and water sterilization techniques have been driving the evolution of life support systems of most of the public seawater aquaria. Their recent progresses have made possible the keeping of fish as large as manta rays and whale sharks. However, by removing all of the plankton and failing to eliminate all of the wastes produced by the fish and the decomposition of organic detritus these techniques alter the composition of the water in the tank. Filtered and sterilized water does not meet the biological requirements of a number of plants and invertebrates that are much more demanding than fish. A few open-circuit aquaria built in pristine near-shore areas have overcome the above-mentioned inconveniences by pumping huge amounts of unpolluted water. But the number of places suitable to accommodate aquaria of this kind is and will remain very limited. Therefore, efforts have been made to adapt to public aquaria natural techniques for maintaining closedcircuit aquaria that hobbyists began to develop empirically in the middle of the fifties. The present paper analyses the processes that underpin the genesis and evolution of one of these techniques, which has been implemented in Monaco to cultivate reefbuilding corals. Cultivated corals were used to improve the exhibition in the aquarium of the Oceanographic Museum but also to carry out scientific experiments, which have resulted in major findings regarding the ecology and physiology of these organisms.